In general, glass is an isotropic amorphous inorganic oxide material. However, Non-Patent Document 1 discloses that when a mixed alkali metaphosphate glass having a specific composition is elongated in one axial direction, an anisotropic glass having an extremely large birefringence is obtained. Non-Patent Document 1 further discloses that the anisotropic glass shows entropic elasticity. The entropic elasticity used herein is a property that restoring force is developed in order that molecules arranged regularly due to external force return to original irregular state according to a law of entropy increase, and is characteristic property of rubber.
Various applications are expected to the anisotropic glass having such a characteristic.
Non-Patent Document 1: Nature Materials Vol. 14, pp 312-317 (2015)